U.S. patent number 6,372,696 [Application Number 09/436,409] was granted by the patent office on 2002-04-16 for traction fluid formulation.
This patent grant is currently assigned to The Lubrizol Corporation. Invention is credited to Craig D. Tipton.
United States Patent |
6,372,696 |
Tipton |
April 16, 2002 |
Traction fluid formulation
Abstract
A traction fluid useful in automotive power transmitting
equipment includes a base fluid of polymers of at least one olefin
which contains 3 to 5 carbon atoms, hydrocarbon molecules
containing non-aromatic cyclic moieties, or mixtures thereof; a
low-temperature viscosity control agent selected from the group
consisting of oligomers or polymers of linear alpha olefins of at
least 8 carbon atoms, naphthenic oils, synthetic ester oils,
polyether oils, and mixtures thereof, in an amount sufficient to
reduce the low temperature viscosity of the traction fluid; and an
additive package including dispersants, detergents, or mixtures
thereof, along with other optional additive components.
Inventors: |
Tipton; Craig D. (Perry,
OH) |
Assignee: |
The Lubrizol Corporation
(Wickliffe, OH)
|
Family
ID: |
23732278 |
Appl.
No.: |
09/436,409 |
Filed: |
November 9, 1999 |
Current U.S.
Class: |
508/110; 252/73;
508/287; 508/391; 525/20; 585/1; 585/16; 585/20 |
Current CPC
Class: |
C10M
111/04 (20130101); C10M 169/04 (20130101); C10M
169/041 (20130101); C10M 171/002 (20130101) |
Current International
Class: |
C10M
111/04 (20060101); C10M 169/00 (20060101); C10M
171/00 (20060101); C10M 111/00 (20060101); C10M
169/04 (20060101); C10M 105/04 () |
Field of
Search: |
;508/110
;585/1,16,20 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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275 313 |
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Dec 1987 |
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EP |
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275 315 |
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Jul 1988 |
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EP |
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295 304 |
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Dec 1988 |
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EP |
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328 642 |
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Aug 1989 |
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EP |
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0 949 319 |
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Oct 1999 |
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EP |
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2 224 287 |
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Mar 1990 |
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GB |
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Other References
Smalheer et al, "Lubricant Additives", p. 1-11, 1967.* .
SAE Technical Paper 1999-01-3614, Huston et al., "Shifting from
Automatic to Continuously Variable Transmissions: A Look at Fluid
Technology Requirements," Oct. 27, 1999. .
SAE Techincal Paper Series 902144, Watts et al., "Formulating
Automatic Transmission Fluids with Improved Low Temperature
Fluidity," Oct., 1990/..
|
Primary Examiner: McAvoy; Ellen M.
Attorney, Agent or Firm: Shold; David M. Esposito; Michael
F.
Claims
What is claimed is:
1. A traction fluid useful in automotive power transmitting
equipment, comprising:
(a) a major amount of a base fluid comprising a predominantly
linear hydrogenated dimer of alpha-alkylstyrene;
(b) a low-temperature viscosity control agent selected from the
group consisting of oligomers or polymers of linear alpha olefins
of at least 8 carbon atoms, naphthenic oils, synthetic ester oils,
polyether oils, and mixtures thereof, in an amount sufficient to
reduce the viscosity at -40.degree. C. of said traction fluid;
and
(c) an additive selected from the group consisting of dispersants,
detergents, and mixtures thereof, in an amount sufficient to
improve the clutch friction durability performance of said traction
fluid.
2. The traction fluid of claim 1 wherein the base fluid has a
viscosity of greater than about 2.5 cSt at 100.degree. C. and the
low-temperature viscosity control agent has a viscosity of up to
about 2.5 cSt at 100.degree. C.
3. The traction fluid of claim 1 wherein said traction fluid
exhibits a viscosity at -40.degree. C. of less than about 100
Pa.multidot.s.
4. The traction fluid of claim 1 wherein said traction fluid
exhibits a viscosity at -40.degree. C. of about 5 to about 70
Pa.multidot.s.
5. The traction fluid of claim 1 wherein components (a) and (b) are
hydrogenated materials.
6. The traction fluid of claim 5 wherein components (a) and (b) are
each substantially free from carbon-carbon unsaturation.
7. The traction fluid of claim 1 wherein said additive (c) includes
a dispersant.
8. The traction fluid of claim 7 wherein the dispersant is a
succinimide dispersant.
9. The traction fluid of claim 7 wherein the amount of said
dispersant is about 1 to about 10 percent by weight of the
composition.
10. The traction fluid of claim 1 wherein said additive (c)
includes a detergent.
11. The traction fluid of claim 10 wherein said detergent is an
overbased sulfonate detergent.
12. The traction fluid of claim 11 wherein said overbased sulfonate
detergent is a calcium overbased sulfonate detergent.
13. The traction fluid of claim 10 wherein the amount of said
detergent is about 0.05 to about 5 percent by weight of the
composition.
14. The traction fluid of claim 1 wherein said additive (c)
includes a succinimide dispersant and a calcium overbased sulfonate
detergent.
15. The traction fluid of claim 1 wherein said fluid contains up to
about 10 percent by weight of a polymeric viscosity index
modifier.
16. The traction fluid of claim 15 wherein said fluid contains 0 to
about 1 percent by weight of a polymeric viscosity index
modifier.
17. The traction fluid of claim 16 wherein said fluid is
substantially free from polymeric viscosity index modifiers.
18. The traction fluid of claim 1 further comprising (d) at least
one phosphorus-containing acid, salt, or ester in an amount to
contribute about 0.005 to about 0.06% phosphorus to the traction
fluid.
19. The traction fluid of claim 18 wherein said
phosphorus-containing acid, salt, or ester comprises dibutyl
hydrogen phosphite.
20. The traction fluid of claim 1 further comprising (e) at least
one friction modifier.
21. The traction fluid of claim 20 wherein the amount of friction
modifier is about 0.01 to about 2 percent by weight.
22. The traction fluid of claim 1 wherein said base fluid comprises
a polymer of isobutylene having a molecular weight of about 200 to
about 700.
23. The composition of claim 1 wherein said base fluid contains a
major proportion of compound represented by the general structure
##STR10##
wherein, each R is an alkyl group of 1 to 4 carbon atoms.
24. The traction fluid of claim 1 wherein said low-temperature
viscosity control agent has a viscosity of less than
2.5.times.10.sup.-6 m.sup.2 /s at 100.degree. C.
25. The traction fluid of claim 1 wherein said low-temperature
viscosity control agent comprises an oligomer or polymer of linear
alpha olefins having 8 to about 16 carbon atoms, said oligomer or
polymer having a molecular weight of about 250 to about 400.
26. The traction fluid of claim 25 wherein said alpha olefins
contain about 10 to about 12 carbon atoms.
27. The traction fluid of claim 1 wherein said low temperature
viscosity control agent comprises a naphthenic oil.
28. The traction fluid of claim 1 wherein said low temperature
viscosity control agent comprises a synthetic ester oil selected
from the group consisting of:
(i) esters of polyhydroxy compounds and predominantly
monocarboxylic acylating agents,
(ii) esters of predominantly monohydroxy compounds and
polycarboxylic acylating agents, and
(iii) esters of monohydroxy compounds and monocarboxylic acylating
agents,
(iv) mixtures of (i) through (iii).
29. The traction fluid of claim 1 wherein said low temperature
viscosity control agent comprises a polyether oil selected from the
group consisting of polyethylene oxides, polypropylene oxides,
polybutylene oxides, and mixtures thereof.
30. A traction fluid prepared by admixing the components of claim
1.
31. A method of lubricating a power transmission apparatus,
comprising employing therein the traction fluid of claim 1.
32. The method of claim 31 wherein said power transmission
apparatus drive is an automatic transmission.
33. The method of claim 32 wherein said automatic transmission is a
continuously variable transmission.
34. The method of claim 31 wherein said power transmission
apparatus is a tracton/drive.
35. The method of claim 31 wherein said power transmission
apparatus is a push-belt continuously variable transmission.
36. The traction fluid of claim 1 wherein said traction fluid
exhibits a viscosity at -40.degree. C. of less than or equal to 224
Pa.multidot.s.
37. The traction fluid of claim 1 wherein said traction fluid
exhibits a viscosity at -30.degree. C. of 11.2 to 24 Pa.multidot.s.
Description
BACKGROUND OF THE INVENTION
The present invention relates to traction fluids and their use in
lubricating power transmitting equipment, especially, a traction
drive, and more specifically, an automotive traction drive.
Traction drives are devices in which power or torque is transmitted
from an input element to an output element through nominal point or
line contact, typically with a rolling action, by virtue of the
traction between the contacting elements. Traction drives can be
generally used in automotive or industrial machinery for
transmitting power between rotating members. They can be used as
automatic transmissions and are particularly suitable as a form of
continuously variable automatic transmission for use in automobile
drivetrains and other applications.
While the working elements of a traction drive are sometimes spoken
of as being in contact, it is generally accepted that a fluid film
must be provided therebetween. Thus, rather than metal-to-metal
rolling contact, a film of fluid is introduced into the load zone,
and power is transmitted by shearing of the film, which may become
very viscous due to the high pressure at the contact area. The
nature and properties of the fluid, therefore, will determine to a
large extent the performance and capacity of the traction drive.
Traction fluids will preferably have a high shear resistance (often
measured as "traction coefficient") to maximize the power
transmission performance. Low viscosity, particularly at low
temperatures, is also desirable for efficient operation under cold
conditions. The fluid should ideally also exhibit good lubricating
properties for and compatibility with other components of the
traction drive. Such fluids also serve to remove heat and prevent
wear at the contact surfaces and to lubricate bearings and other
moving parts associated with the drive.
Traction fluids based on a variety of base fluids are known. For
example, U.S. Pat. No. 5,043,497, Muraki et al., Aug. 27, 1991,
discloses a lubricating oil for a traction drive, mainly composed
of a naphthenic hydrocarbon having 19 carbon atoms comprising two
substituted cyclohexane rings linked by a methylene group.
Additives for ordinary lubricating oils such as antioxidants,
agents for increasing the viscosity index, corrosion inhibitors,
detergents, defoamers, and so forth are added as necessary. Calcium
sulfonate is disclosed as a detergent.
U.S. Pat. No. 3,975,278, Wygant, Aug. 17, 1976, discloses
hydrogenated dimers of a-alkyl styrene, which are useful as
tractive fluids. Additives such as VI improvers, antioxidants,
antiwear agents, corrosion inhibitors, dispersants, and dyes can be
included.
U.S. Pat. No. 3,966,624, Duling et al., Jun. 29, 1976, discloses a
blended traction fluid containing hydrogenated polyolefin and an
adamantane ether. The lubricant described can contain other oils
and additives, e.g., a sludge dispersant. An especially useful
additive, combining detergency, corrosion inhibition and friction
improvement at high speeds, is a Mg, Ca or Ba salt (especially a
super-based salt) of certain weak acids.
A variety of additive formulation for use in transmission fluids
and other functional fluids are generally known. For instance, U.S.
Pat. No. 5,858,929, Sumiejski et al., Jan. 12, 1999, equivalent to
European Patent publication 747,464, published Jun. 6, 1996,
discloses a composition for use in lubricants and functional fluids
to provide improved anti-shudder and shudder durability properties
to an automatic transmission. The composition comprises alkoxylated
fatty amines as well as a mixture of other friction modifiers.
Preferred compositions include alkoxylated fatty amines, other
friction modifiers, antioxidants, overbased metal organic acid,
dispersants, viscosity index improver and/or dispersant-viscosity
modifier, extreme pressure agent, seal swell agent, and 85%
phosphoric acid. The base oils of lubricating viscosity include
liquid petroleum oils and solvent treated or acid treated mineral
lubricating oils of the paraffinic, naphthenic or mixed
naphthenic-paraffinic types.
The present invention solves the problem of providing a fluid for a
traction drive with a sufficiently high traction coefficient to
maintain the efficiency of the unit, while at the same time
providing a low enough viscosity that the unit will operate at
ambient temperatures in cold climates. Additionally, the presence
of suitable additives provides lubrication and compatibility of the
fluid with the operation of conventional clutches, seals, and gears
which may be present in the traction drive unit. The traction
fluids of the present invention can also be used in other types of
power transmission devices such as continuously variable
transmissions of the push-belt type. Push-belt continuously
variable transmissions are described in U.S. Pat. No.
5,750,477.
SUMMARY OF THE INVENTION
The present invention provides a traction fluid useful in
automotive power transmitting equipment, comprising (a) a major
amount of a base fluid selected from the group consisting of
polymers of at least one olefin which contains 3 to 5 carbon atoms,
hydrocarbon or ester molecules containing non-aromatic cyclic
moieties, and mixtures thereof; (b) a low-temperature viscosity
control agent selected from the group consisting of oligomers or
polymers of linear alpha olefins of at least 8 carbon atoms,
naphthenic oils, synthetic ester oils, polyether oils, and mixtures
thereof, in an amount sufficient to reduce the viscosity at
-40.degree. C. of said traction fluid; and (c) an additive selected
from the group consisting of dispersants, detergents, and mixtures
thereof, in an amount sufficient to improve the clutch friction
durability performance of said traction fluid.
The present invention also provides a method of lubricating a power
transmission apparatus such as a traction drive, comprising
employing therein the above-described traction fluid.
DETAILED DESCRIPTION OF THE INVENTION
Various preferred features and embodiments will be described below
by way of non-limiting illustration.
The first, and major component of the traction fluids of the
present invention is a base fluid or base oil. Certain types of
base fluids are particularly suited for use in traction fluids
because of their inherently good (high) traction coefficients. Two
types of base fluids which are particularly suitable are (1)
polymers of at least one olefin which contains 3 to 5 carbon atoms,
and (2) hydrocarbon molecules containing non-aromatic cyclic
moieties. Mixtures of these types of materials can also be used.
For suitable performance, the base fluid should preferably have a
viscosity of greater than 2.5.times.10.sup.-6 m.sup.2 /s (2.5 cSt)
at 100.degree. C. (ASTM D-445), and more preferably a viscosity of
at least 3.0.times.10.sup.-6 m.sup.2 /s (3.0 cSt) or
3.5.times.10.sup.-6 m.sup.2 /s (3.5 cSt), typically up to
8.0.times.10.sup.-6 m.sup.2 /s (8.0 cSt) or 7.0.times.10.sup.-6
m.sup.2 /s (7.0 cSt) or 6.0.times.10.sup.-6 m.sup.2 /s (6.0 cSt) at
100.degree. C.
Suitable base fluids of type (1) include polymers of branched
olefins, preferably isobutylene, particularly those having a number
average molecular weight of 180 to 2000, preferably 200 to 1000 or
to 700. The polymer is preferably hydrogenated to remove any
residual unsaturation. Such materials and their preparation are
well known and are described, for instance, in U.S. Pat. No.
3,966,624, as component A, described particularly in column 12 line
32 through column 16 line 11.
Suitable base fluids of type (2) include a wide variety of
cyclic-containing hydrocarbon molecules. Examples of these include
di(cyclohexyl)alkanes, cyclohexyl hydrindans and adamantane
compounds, as described in U.S. Pat. No. 3,966,624; esters of
cyclohexanol and cylohexanecarboxylic acid, as described in U.S.
Pat. No. 4,871,476; decalin, cycohexyldecalin, alkyl-substituted
decalin, alkyl-substituted cyclohexyldecalin, and mixtures thereof,
as described in U.S. Pat. No. 3,803,037; various materials having
two cyclohexane rings linked by a methylene group described in U.S.
Pat. No. 5,043,497; various hydrocarbon compounds having a
bicyclooctane skeleton described in U.S. Pat. No. 5,422,027;
hydrogenated products of dimers, trimers, or tetramers of
norbornanes and/or norbornenes described in U.S. Pat. No.
5,126,065; hydrogenated dimers, trimers, or polymers of cyclic
monoterpenoid monomers described in U.S. Pat. No. 4,975,215;
various ter-cyclohexyl compounds disclosed in U.S. Pat. No.
5,850,745; perhydrofluorene derivatives disclosed in U.S. Pat. No.
4,774,013; and preferably linear dimers of hydrogenated
.alpha.-alkyl styrene, as described in U.S. Pat. No. 3,975,278. Any
of the above materials may be used in a hydrogenated form, to
assure the removal of carbon unsaturation; indeed, certain
hydrogenated styrene derivatives (or cyclohexane derivatives) are
inherently hydrogenated species. However, aromatic cyclic
structures such as those derived from styrene may also be present
in the base fluid, since aromatic cyclic structures are generally
considered to be less deleterious than olefinic unsaturation.
The preferred materials for option (2) of the base fluid are
predominantly linear dimers of hydrogenated .alpha.-alkyl styrene.
These dimers are said to be predominantly linear, in contrast to
the cyclic dimers which represent another possible structure. Such
preferred materials can be represented by the general structure
##STR1##
wherein each R is an alkyl group of 1 to 4 carbon atoms and C.sub.6
H.sub.11 represents a cyclohexyl group. Such materials and their
preparation are described in detail in U.S. Pat. No. 3,975,278.
Indeed, the base fluid for the present composition preferably
contains a major proportion of compounds represented as shown
above.
The amount of the base fluid is a major amount of the traction
fluid. By "a major amount" is meant at least 50 percent by weight
of the fluid. Preferably the base fluid comprises 70 to 95 percent
by weight of the fluid, more preferably 75 to 90 percent by weight,
and still more preferably 80 to 85 percent by weight.
A second component of the present traction fluids is a
low-temperature viscosity control agent. The low-temperature
viscosity control agent (which is to be distinguished from a
viscosity index modifier, an optional component described below) is
selected from among a variety of materials which are known to be
useful for this purpose. The low-temperature viscosity control
agent is selected from (a) oligomers or polymers of linear alpha
olefins of at least 8 carbon atoms, (b) naphthenic oils, (c)
synthetic ester oils, (d) polyether oils, and mixtures thereof.
These materials are distinguishable from the base fluids, described
above, in that they are generally lower viscosity materials than
the base fluid, typically exhibiting a viscosity of up to or less
than 2.5.times.10.sup.-6 m.sup.2 /s (2.5 cSt), preferably 1.5 to
2.5, or 1.8 to 2.3.times.10.sup.-6 m2/s (1.5 to 2.5 or 1.8 to 2.3
cSt) at 100.degree. C. These are also materials which typically
retain a measure of mobility at low temperatures (e.g., -40.degree.
C.) and can serve to reduce the low temperature viscosity of fluids
to which they are added. Materials which are of unduly high
viscosity or which do not retain mobility at low temperatures do
not effectively serve as low-temperature viscosity control agents.
Determination of viscosity and low temperature mobility is well
within the abilities of those skilled in the art.
Polymers and oligomers of linear .alpha.-olefins are well known
items of commerce. A typical commercial material is Ethylflo.TM.
162, a 2.times.10.sup.-6 m.sup.2 /s (2 cSt) poly .alpha.-olefin
product of Ethyl Corporation Preferred materials are those
oligomers or polymers of .alpha.-olefins containing 8 to 16 carbon
atoms, and preferably 10 to 12 carbon atoms. Such materials do not
contain a significant fraction of .alpha.-olefin monomers of fewer
than 8 carbon atoms, that is, less than 5 percent by weight,
preferably less than 1 percent by weight, and more preferably
substantially no such monomers. Thus common materials such as
ethylene-octene polymers, where the ethylene predominates, are
excluded from use as low temperature viscosity modifiers in the
materials of the present invention. The description "oligomers or
polymers" is used since generally low molecular weight materials
are desired, and there is otherwise no clear demarcation between an
oligomer and a polymer. Materials as low as dimers (a degree of
polymerization of 2) are included. Suitable materials for the
present invention typically have a molecular weight range of 100 to
1000, preferably 150 to 600, and most preferably 250 to 500 or 250
to 400.
Naphthenic oils are well known items of commerce, commonly derived
from petroleum. Preferred materials are hydrogenated naphthenic
oils, which are also well known. Examples include Hydrocal.TM.38,
from Calumet Lubricants Company and 40 Pale Oil.TM. from Diamond
Shamrock. Synthetic ester oils suitable for use as low temperature
viscosity control agents include esters of polyhydroxy compounds
and predominantly monocarboxylic acylating agents; esters of
predominantly monohydroxy compounds and polycarboxylic acylating
agents; esters of monohydroxy compounds and monocarboxylic
acylating agents, and mixtures of the foregoing types. The prefix
"poly" in this context indicates at least two hydroxy groups or
carboxylic groups, as the case may be. The molecular weight of the
esters (as of any of the viscosity control agents) should be
sufficiently high that the materials are not objectionably volatile
so as to be subject to significant evaporative loss under operating
conditions, while retaining the above-described viscosities.
Certain synthetic ester oils and their methods of preparation are
disclosed in PCT publication WO 91/13133. Synthetic ester oils are
available as Emery.TM. synthetic lubricant basestocks, from Henkel
Corporation and as Emkarate.TM. lubricant basestocks from Imperial
Chemical Industries PLC.
Polyether oils suitable for use as low temperature viscosity
control agent include polyalkylene oxides, and in particular,
polyethylene oxides, polypropylene oxides, polybutylene oxides, and
mixtures thereof. The polyether oil will typically have a molecular
weight in the ranges suitable for maintaining an appropriate
viscosity and non-volatility. Such materials are also well known
items of commerce and are available as Emkarox.TM. polyalkylene
glycols from Imperial Chemical Industries PLC.
As is the case with the base fluid, the low temperature viscosity
control agent is often a hydrogenated material. Each of these
components will preferably contain fewer than 20%, fewer than 15%,
or more preferably fewer than 10% molecules containing
carbon-carbon unsaturation, and in the most preferred case will be
substantially free from carbon-carbon unsaturation, that is to say,
retaining at most a low level of unsaturation which does not
measurably or significantly affect its performance.
The amount of the low temperature viscosity control agent in the
traction fluid is preferably that amount suitable to provide a
viscosity at -40.degree. C. of less than or equal to 100
Pa.multidot.s (100,000 cP), such as 2-100 Pa.multidot.s (2,000 to
100,000 cP), preferably 5 to 80 or 70 Pas (5,000 to 80,000 or
70,000 cP), and more preferably 10 to 50 Pa.multidot.s (10,000 to
50,000 cP). Otherwise expressed, the amount of low temperature
viscosity control agent should preferably 1 to 20 percent by weight
of the traction fluid, preferably 3 to 15, and more preferably 5 to
10 percent by weight.
In addition to the base fluid and low-temperature viscosity control
agent, the traction fluid of the present invention will contain an
additive which includes at least one dispersant, or at least one
detergent, or mixtures thereof. Dispersants and detergents are
extremely well-known and commonly used materials in the field of
lubrication. The amount of such additive is that which is
sufficient to improve the clutch friction durability performance of
the traction fluid, compared to the performance in the absence of
such additive. The amount of this additive (including the detergent
and the dispersant, if both are present) is preferably up to 20
percent by weight of the traction fluid, preferably 5 to 15 percent
by weight.
The dispersants useful as a component in the present fluids include
acylated amines, carboxylic esters, Mannich reaction products,
hydrocarbyl substituted amines, and mixtures thereof.
Acylated amine dispersants include reaction products of one or more
carboxylic acylating agent and one or more amine. The carboxylic
acylating agents include C.sub.8-30 fatty acids, C.sub.14-20
isoaliphatic acids, C.sub.18-44 dimer acids, addition dicarboxylic
acids, trimer acids, addition tricarboxylic acids, and hydrocarbyl
substituted carboxylic acylating agents. Dimer acids are described
in U.S. Pat. Nos. 2,482,760, 2,482,761, 2,731,481, 2,793,219,
2,964,545, 2,978,468, 3,157,681, and 3,256,304. The addition
carboxylic acylating agents are addition (4+2 and 2+2) products of
an unsaturated fatty acid with one or more unsaturated carboxylic
reagents. These acids are taught in U.S. Pat. No. 2,444,328. In
another embodiment, the carboxylic acylating agent is a hydrocarbyl
substituted carboxylic acylating agent. The hydrocarbyl substituted
carboxylic acylating agents are prepared by a reaction of one or
more of olefins or polyalkenes with one or more of unsaturated
carboxylic agents, such as itaconic, citraconic, or maleic
acylating agents, typically at a temperature of 160.degree., or
185.degree. C. up to 240.degree. C., or to 210.degree. C. Maleic
acylating agents are the preferred unsaturated acylating agent. The
procedures for preparing the acylating agents are well known to
those skilled in the art and have been described for example in
U.S. Pat. No. 3,412,111; and Ben et al, "The Ene Reaction of Maleic
Anhydride With Alkenes", J. C. S. Perkin II (1977), pages
535-537.
The amines which react with the acylating agents may be known
amines, preferably a polyamine, such as an alkylenepolyamine or a
condensed polyamine. Polyamines can be aliphatic, cycloaliphatic,
heterocyclic or aromatic., Examples of the polyamines include
alkylene polyamines, hydroxy containing polyamines, arylpolyamines,
and heterocyclic polyamines.
Alkylene polyamines are represented by the formula ##STR2##
wherein n has an average value from 1 or 2 to 10, or to 7, or to 5,
and the "Alkylene" group has from 1 or 2 to 10, or to 6, or to 4
carbon atoms. Each R is independently hydrogen, or an aliphatic or
hydroxy-substituted aliphatic group of up to 30 carbon atoms.
Acylated amines, their intermediates and methods for preparing the
same are described in U.S. Pat. Nos. 3,219,666; 4,234,435;
4,952,328; 4,938,881; 4,957,649; 4,904,401; and 5,053,152.
In another embodiment, the dispersant can be a carboxylic ester.
The carboxylic ester is prepared by reacting at least one or more
carboxylic acylating agents, preferably a hydrocarbyl substituted
carboxylic acylating agent, with at least one organic hydroky
compound and optionally an amine. The hydroxy compound may be an
alcohol or a hydroxy containing amine.
The alcohols may contain non-hydrocarbon substituents of a type
which do not interfere with the reaction of the alcohols with the
acid (or corresponding acylating agent) to form the ester. In one
embodiment, the alcohols can be polyhydric alcohols, such as
alkylene polyols. Preferably, such polyhydric alcohols contain from
2 to 40 carbon atoms, more preferably 2 to 20; and from 2 to 10
hydroxyl groups, more preferably 2 to 6. Polyhydric alcohols
include ethylene glycols, including di-, tri- and tetraethylene
glycols; propylene glycols, including di-, tri- and tetrapropylene
glycols; glycerol; butane diol; hexane diol; sorbitol; arabitol;
mannitol; cyclohexane diol; erythritol; and pentaerythritols,
including di- and tripentaerythritol; preferably, diethylene
glycol, triethylene glycol, glycerol, sorbitol, pentaerythritol and
dipentaerythritol. Commercially available polyoxyalkylene alcohol
demulsifiers can also be employed as the alcohol component.
The carboxylic ester dispersants may be prepared by any of several
known methods. The method which is preferred because of convenience
and the superior properties of the esters it produces, involves the
reaction of the carboxylic acylating agents described above with
one or more alcohol or phenol in ratios from 0.5 equivalent to 4
equivalents of hydroxy compound per equivalent of acylating agent.
The preparation of useful carboxylic ester dispersant is described
in U.S. Pat. Nos. 3,522,179 and 4,234,435.
The carboxylic ester dispersants may be further reacted with at
least one of the above described amines and preferably at least one
of the above described polyamines, such as a polyethylenepolyamine,
condensed polyamine, or a heterocyclic amine, such as
aminopropylmopholine. The amine is added in an amount sufficient to
neutralize any non-esterified carboxyl groups. In one embodiment,
the carboxylic ester dispersants are prepared by reacting from 1 to
2 equivalents, or from 1.0 to 1.8 equivalents of hydroxy compounds,
and up to 0.3 equivalent, or from 0.02 to 0.25 equivalent of
polyamine per equivalent of acylating agent. The carboxylic acid
acylating agent may be reacted simultaneously with both the hydroxy
compound and the amine. There is generally at least 0.01 equivalent
of the alcohol and at least 0.01 equivalent of the amine although
he total amount of equivalents of the combination should be at
least 0.5 equivalent per equivalent of acylating agent. These
carboxylic ester dispersant compositions are known in the art, and
the preparation of a number of these derivatives is described in,
for example, U.S. Pat. Nos. 3,957,854 and 4,234,435.
In another embodiment, the dispersant may also be a
hydrocarbyl-substituted amine. These hydrocarbyl-substituted,amines
are well known to those skilled in the art. These amines and
methods for their preparation are disclosed in U.S. Pat. Nos.
3,275,554; 3,438,757; 3,454,555; 3,565,804; 3,755,433; and
3,822,289. Typically, hydrocarbyl substituted amines are prepared
by reacting olefins and olefin polymers, including the above
polyalkenes and halogenated derivatives thereof, with amines (mono-
or polyamines). The amines may be any of the amines described
above, preferably an alkylenepolyamine. Examples of hydrocarbyl
substituted amines include ethylenepolyamines such as
diethylenetriamine; poly(propylene)amine;
N,N-dimethyl-N-poly(ethylene/propylene)-amine, (50:50 mole ratio of
monomers); polybutene amine; N,N-di(hydroxyethyl)-N-polybutene
amine; N-(2-hydroxypropyl)-N-polybutene amine;
N-polybutene-aniline; N-polybutenemorpholine;
N-poly(butene)-ethylenediamine;
N-poly(propylene)trimethylenediamine;
N-poly(butene)-diethylenetriamine;
N',N"-poly(butene)tetraethylenepentamine; and
N,N-dimethyl-N'-poly(propylene)-1,3-propylenediamine.
In another embodiment, the dispersant may also be a Mannich
dispersant. Mannich dispersants are generally formed by the
reaction of at least one aldehyde, such as formaldehyde and
paraformaldehyde, at least one of the above described amines,
preferably a polyamine, such as a polyalkylenepolyamine, and at
least one alkyl substituted hydroxyaromatic compound. The amounts
of the reagents is such that the molar ratio of hydroxyaromatic
compound to formaldehyde to amine is in the range from (1:1:1) to
(1:3:3). The hydroxyaromatic compound is generally an alkyl
substituted hydroxyaromatic compound. This term includes the above
described phenols. The hydroxyaromatic compounds are those
substituted with at least one, and preferably not more than two,
aliphatic or alicyclic groups having from 6 to 400, or from 30 to
300, or from 50 to 200 carbon atoms. These groups may be derived
from one or more of the above described olefins or polyalkenes. In
one embodiment, the hydroxyaromatic compound is a phenol
substituted with an aliphatic or alicyclic hydrocarbon-based group
having an M.sub.n of 420 to 10,000. Mannich dispersants are
described in the following patents: U.S. Pat. No. 3,980,569; U.S.
Pat. No. 3,877,899; and U.S. Pat. No. 4,454,059.
The dispersant can also be a dispersant which has been treated or
reacted with any of a variety of common agents. In one embodiment,
the boron compound is a borated dispersant. Typically, a borated
dispersant contains 0.1% to 5%, or 0.5% to 4%, or 0.7% to 3% by
weight boron. In one embodiment, the borated dispersant is a
borated acylated amine, such as a borated succinimide dispersant.
Borated dispersants are described in U.S. Pat. Nos. 3,000,916;
3,087,936; 3,254,025; 3,282,955; 3,313,727; 3,491,025; 3,533,945;
3,666,662 and 4,925,983. Borated dispersant are prepared by
reaction of one or more dispersant with one or more boron compounds
such as an alkali or mixed alkali metal and alkaline earth metal
borate. These metal borates are generally a hydrated particulate
metal borate which are known in the art. Alkali metal borates
include mixed alkali and alkaline metal borates. These metal
borates are available commercially.
Dispersants can also be treated by or reacted with other agents to
produce well-known variants. Such agent include sulfurizing agents
such as elemental sulfur or CS.sub.2 and dimercaptothiadizoles.
Reactions of dispersants with a dimer-capto-thiadiazole is taught,
for example, in U.S. Pat. No. 4,136,043.
The amount of the dispersant in the traction fluid composition is
preferably 1 to 10 weight percent, preferably 1.5 to 7 weight
percent, and more preferably 2 to 3 weight percent.
The additive component for the traction fluid can also contain one
or more detergents, which are normally salts, and specifically
overbased salts. Overbased salts, or overbased materials, are
single phase, homogeneous Newtonian systems characterized by a
metal content in excess of that which would be present according to
the stoichiometry of the metal and the particular acidic organic
compound reacted with the metal.
The amount of excess metal is commonly expressed in terms of metal
ratio. The term "metal ratio" is the ratio of the total equivalents
of the metal to the equivalents of the acidic organic compound. A
neutral metal salt has a metal ratio of one. A salt having 4.5
times as much metal as present in a normal salt will have metal
excess of 3.5 equivalents, or a ratio of 4.5. The basic salts of
the present invention have a metal ratio of 1.5, more preferably 3,
more preferably 7, up to 40, preferably 25, more preferably 20.
The basicity of the overbased materials of the present invention
generally is expressed in terms of a total base number. A total
base number is the amount of acid (perchloric or hydrochloric)
needed to neutralize all of the overbased material's basicity. The
amount of acid is expressed as potassium hydroxide equivalents (mg
KOH per gram of sample). Total base number is determined by
titration of one gram of overbased material with 0.1 Normal
hydrochloric acid solution using bromophenol blue as an indicator.
The overbased materials of the present invention generally have a
total base number of at least 20, preferably 100, morepreferably
200. The overbased material generally have a total base number up
to 600, preferably 500, more preferably 400.
The overbased materials are prepared by reacting an acidic material
(typically an inorganic acid or lower carboxylic acid, preferably
carbon dioxide) with a mixture comprising an acidic organic
compound, a reaction medium comprising at least one inert, organic
solvent (such as mineral oil, naphtha, toluene, xylene) for said
acidic organic material, a stoichiometric excess of a metal base,
and a promoter.
The acidic organic compounds useful in making the overbased
compositions of the present invention include carboxylic acids,
sulfonic acids, phosphorus-containing acids, phenols or mixtures
thereof. Preferably, the acidic organic compounds are carboxylic
acids or sulfonic acids with sulfonic and salicylic acids more
preferred. Reference to acids, such as carboxylic, or sulfonic
acids, is intended to include the acid-producing derivatives
thereof such as anhydrides, lower alkyl esters, acyl halides,
lactones and mixtures thereof unless otherwise specifically
stated.
The carboxylic acids useful in making the overbased salts (A) of
the invention can be aliphatic or aromatic, mono- or polycarboxylic
acid or acid-producing compounds. These carboxylic acids include
lower molecular weight carboxylic acids (e.g., carboxylic acids
having up to 22 carbon atoms such as acids having 4 to 22 carbon
atoms or tetrapropenyl-substituted succinic anhydride) as well as
higher molecular weight carboxylic acids. The carboxylic acids of
this invention are preferably oil-soluble. Usually, in order to
provide the desired oil-solubility, the number of carbon atoms in
the carboxylic acid should be at least 8, more preferably at least
18, more preferably at least 30, more preferably at least 50.
Generally, these carboxylic acids do not contain more than 400
carbon atoms per molecule.
The lower molecular weight monocarboxylic acids contemplated for
use in this invention include saturated and unsaturated acids.
Examples of such useful acids include dodecanoic acid, decanoic
acid, oleic acid, stearic acid, linoleic acid, and tall oil acid.
Monocarboxylic acids include isoaliphatic acids, often containing a
principal chain having from 14 to 20 saturated, aliphatic carbon
atoms and at least one but usually no more than four pendant
acyclic lower alkyl groups. Specific examples of isoaliphatic acids
include 10-methyltetradecanoic acid, 3-ethylhexadecanoic acid, and
8-methyloctadecanoic acid.
High molecular weight carboxylic acids can also be used in the
present invention. These acids have a substituent group derived
from a polyalkene. The polyalkene is characterized as containing at
least 30 carbon atoms, preferably at least 35, more preferably at
least 50, and up to 300 carbon atoms, preferably 200, more
preferably 150. In one embodiment, the polyalkene is characterized
by an M.sub.n value of at least 500, generally 500 to 5000,
preferably 800 to 2500. In another embodiment, M.sub.n varies
between 500 and 1200 or 1300. The higher molecular weight mono- and
polycarboxylic acids suitable for use in making the overbased salts
are well known in the art and have been described in detail, for
example, in U.S. Pat. Nos. 3,024,237; 3,172,892; 3,219,666;
3,245,910; 3,271,310; 3,272,746; 3,278,550; 3,306,907; 3,312,619;
3,341,542; 3,367,943; 3,374,174; 3,381,022; 3,454,607; 3,470,098;
3,630,902; 3,755,169; 3,912,764; and 4,368,133; British Patents
944,136; 1,085,903; 1,162,436; and 1,440,219; and Canadian Patent
956,397.
Illustrative carboxylic acids include palmitic acid, stearic acid,
myristic acid, oleic acid, linoleic acid, behenic acid,
hexatriacontanoic acid, tetrapropylenyl-substituted glutaric acid,
polybutenyl-substituted succinic acid derived from a polybutene
(M.sub.n =200-1500, preferably 300-1000), polypropenyl-substituted
succinic acid derived from a polypropene, (M.sub.n =200-1000,
preferably 300-900), octadecyl-substituted adipic acid,
chlorostearic acid, 9-methylstearic acid, dichlorostearic acid,
stearyl-benzoic acid, eicosanyl-substituted naphthoic acid,
dilauryl-decahydronaphthalene carboxylic acid, mixtures of any of
these acids, their alkali and alkaline earth metal salts, and/or
their anhydrides. A preferred group of aliphatic carboxylic acids
includes the saturated and unsaturated higher fatty acids
containing 12 to 30 carbon atoms. Illustrative of these acids are
lauric acid, palmitic acid, oleic acid, linoleic acid, linoleic
acid, oleostearic acid, stearic acid, myristic acid, and
undecylenic acid, alpha-chlorostearic acid, and alphanitrolauric
acid.
In another embodiment, the carboxylic acids are aromatic carboxylic
acids. A group of useful aromatic carboxylic acids are those of the
formula ##STR3##
wherein R.sub.1 is an aliphatic hydrocarbyl group of preferably 4
to 400 carbon atoms, a is a number of zero to 4, usually 1 or 2, Ar
is an aromatic group, each X is independently sulfur or oxygen,
preferably oxygen, b is a number of 1 to 4, usually 1 or 2, c is a
number of zero to 4, usually 1 to 2, with the proviso that the sum
of a, b and c does not exceed the number o f valences of Ar.
Preferably, R.sub.1 and a are such that there is an average of at
least 8 aliphatic carbon atoms provided by the R.sub.1 groups.
Examples of aromatic carboxylic acids include substituted and
non-substituted benzoic, phthalic and salicylic acids or
anhydrides.
Examples of the aromatic groups that are useful herein include the
polyvalent aromatic groups derived from benzene, naphthalene, and
anthracene, preferably benzene. Specific examples of Ar groups
include phenylenes and naphthylene, e.g., methylphenylenes,
ethoxyphenylenes, isopropylphenylenes, hydroxyphenylenes, and
dipropoxynaphthylenes.
Within this group of aromatic acids, a useful class of carboxylic
acids are those of the formula ##STR4##
wherein R.sub.1 is defined above, a is zero to 4, preferably 1 to
2; b is 1 to 4, preferably 1 to 2, c is zero to 4, preferably 1 to
2, and more preferably 1; with the proviso that the sum of a, b and
c does not exceed 6. Preferably, R.sub.1 and a are such that the
acid molecules contain at least an average of 12 aliphatic carbon
atoms in the aliphatic hydrocarbon substituents per acid molecule.
Preferably, b and c are each one and the carboxylic acid is a
salicylic acid.
The sulfonic acids useful in making the overbased salts of the
invention include the sulfonic and thiosulfonic acids. Generally
they are salts of sulfonic acids. The sulfonic acids include the
mono- or polynuclear aromatic or cycloaliphatic compounds. The
oil-soluble sulfonates can be represented for the most part by one
of the following formulae: R.sub.2 --T--(SO.sub.3.sup.-).sub.a and
R.sub.3 --(SO.sub.3.sup.-).sub.b, wherein T is a cyclic nucleus
such as, for example, benzene, naphthalene, anthracene, diphenylene
oxide, diphenylene sulfide, or petroleum naphthenes; R.sub.2 is an
aliphatic group such as alkyl, alkenyl, alkoxy, or alkoxyalkyl;
(R.sub.2)+T contains a total of at least 15 carbon atoms; and
R.sub.3 is an aliphatic hydrocarbyl group containing at least 15
carbon atoms. Examples of R.sub.3 are alkyl, alkenyl, alkoxyalkyl,
and carboalkoxyalkyl. Specific examples of R.sub.3 are groups
derived from petrolatum, saturated and unsaturated paraffin wax,
and the above-described polyalkenes. The groups T, R.sub.2, and
R.sub.3 in the above Formulae can also contain other inorganic or
organic substituents in addition to those enumerated above such as,
for example, hydroxy, mercapto, halogen, nitro, amino, nitroso,
sulfide, and disulfide. In the above Formulae, a and b are at least
1. In one embodiment, the sulfonic acids have a substituent
(R.sub.2 or R.sub.3) which is derived from one of the
above-described polyalkenes.
Illustrative examples of these sulfonic acids include
monoeicosanyl-substituted naphthalene sulfonic acids,
dodecylbenzene sulfonic acids, didode-cylbenzene sulfonic acids,
dinonylbenzene sulfonic acids, dilauryl betanaphthalene sulfonic
acids, the sulfonic acid derived by the treatment of polybutene
having a number average molecular weight (M.sub.n) in the range of
500 to 5000, preferably 800 to 2000, more preferably 1500 with
chlorosulfonic acid, nitronaphthalene sulfonic acid, paraffin wax
sulfonic acid, cetyl-cyclopentane sulfonic acid, lauryl-cyclohexane
sulfonic acids, or polyethylenyl-substituted sulfonic acids derived
from polyethylene (M.sub.n =300-1000, preferably 750). Normally the
aliphatic groups will be alkyl and/or alkenyl groups such that the
total number of aliphatic carbons is at least 8, preferably at
least 12 up to 400 carbon atoms, preferably 250.
Another group of sulfonic acids are mono-, di-, and tri-alkylated
benzene and naphthalene (including hydrogenated forms thereof)
sulfonic acids. Illustrative of synthetically produced alkylated
benzene and naphthalene sulfonic acids are those containing alkyl
substituents having from 8 to 30 carbon atoms, preferably 12 to 30
carbon atoms, and advantageously about 24 carbon atoms. Such acids
include di-isododecyl-benzene sulfonic acid,
polybutenyl-substituted benzenesulfonic acid,
polypropylenyl-substituted benzenesulfonic acids derived from
polypropene having an M.sub.n =300-1000, preferably 500-700,
cetyl-chlorobenzene sulfonic acid, di-cetylnaphthalene sulfonic
acid, di-lauryldiphenylether sulfonic acid, diisononylbenzene
sulfonic acid, di-isooctadecylbenzene sulfonic acid, and
stearylnaphthalene sulfonic acid.
Dodecyl benzene "bottoms" sulfonic acids can also be used. These
are the material leftover after the removal of dodecyl benzene
sulfonic acids that are used for household detergents. These
materials are generally alkyiated with higher oligomers. The
bottoms may be straight-chain or branched-chain alkylates with a
straight-chain dialkylate preferred.
The production of sulfonates from detergent manufactured
by-products by reaction with, e.g., SO.sub.3, is well known to
those skilled in the art. See, for example, the article
"Sulfonates" in Kirk-Othmer "Encyclopedia of Chemical Technology",
Second Edition, Vol. 19, pp. 291 et seq. published by John Wiley
& Sons, N.Y. (1969).
The phosphorus-containing acids useful in making the basic metal
salts (A) of the present invention include any phosphorus acids
such as phosphoric acid or esters; and thiophosphorus acids or
esters, including mono and dithiophosphorus acids or esters.
Preferably, the phosphorus acids or esters contain at least one,
preferably two, hydrdcarbyl groups containing from 1 to 50 carbon
atoms, typically 1 to 30, preferably 3 to 18, more preferably 4 to
8.
In one embodiment, the phosphorus-containing acids are
dithiophosphoric acids which are readily obtainable by the reaction
of phosphorus pentasulfide (P.sub.2 S.sub.5) and an alcohol or a
phenol. The reaction involves mixing at a temperature of 20.degree.
C. to 200.degree. C. four moles of alcohol or a phenol with one
mole of phosphorus pentasulfide. The oxygen-containing analogs of
these acids are conveniently prepared by treating the dithioic acid
with water or steam which, in effect, replaces one or both of the
sulfur atoms with oxygen.
In another embodiment, the phosphorus-containing acid is the
reaction product of a polyalkene and phosphorus sulfide. Useful
phosphorus sulfide-containing sources include phosphorus
pentasulfide, phosphorus sesquisulfide, and phosphorus
heptasulfide.
The phenols useful in making the basic metal salts (A) of the
invention can be represented by the formula (R.sub.1).sub.a
--Ar--(OH).sub.b, wherein R.sub.1 is defined above; Ar is an
aromatic group; a and b are independently numbers of at least one,
the sum of a and b being in the range of two up to the number of
displaceable hydrogens on the aromatic nucleus or nuclei of Ar.
Preferably, a and b are independently numbers in the range of 1 to
4, more preferably 1 to 2. R.sub.1 and a are preferably such that
there is an average of at least 8 aliphatic carbon atoms provided
by the R.sub.1 groups for each phenol compound.
While the term "phenol" is used herein, it is to be understood that
this term is not intended to limit the aromatic group of the phenol
to benzene. Accordingly, it is to be understood that the aromatic
group as represented by "Ar", as well as elsewhere in other
formulae in this specification and in the appended claims, can be
mononuclear such as a phenyl, a pyridyl, or a thienyl, or
polynuclear. The polynuclear groups can be of the fused type
wherein an aromatic nucleus is fused at two points to another
nucleus such as found in naphthyl or anthranyl. The polynuclear
group can also be of the linked type wherein at least two nuclei
(either mononuclear or polynuclear) are linked through bridging
linkages to each other. These bridging linkages can be chosen from
the group consisting of alkylene linkages, ether linkages, keto
linkages, sulfide linkages, polysulfide linkages of 2 to 6 sulfur
atoms, or a direct carbon-carbon linkage between the groups without
any intervening atoms.
The acid to be overbased can be present as the acid itself, or it
can be supplied in the form of an alternative source for such acid,
that is, another material which will react under the conditions of
the overbasing to produce the desired overbased product, possibly
by means of forming the actual acid as an intermediate in situ.
Thus, for example, suitable acid sources include the acids
themselves as well as esters, amides, anhydrides, and salts of the
acids. A preferred acid source is the vegetable oil based on the
acid, e.g., palm oil, or coconut oil. The source can likewise be a
hydrogenated vegetable oil, derived from an unsaturated vegetable
oil. Vegetable oils are generally triglycerides. In the alkaline
environment of the overbasing reaction, the oils are believed to be
saponified to form the salt, which is then overbased, although the
present invention is not intended to be limited by any such
theoretical explanation.
The metal compounds useful in making the basic metal salts are
generally any Group 1 or Group 2 metal compounds (CAS version of
the Periodic Table of the Elements). The Group 1 metals of the
metal compound include Group 1a alkali metals (e.g., sodium,
potassium, lithium) as well as Group 1b metals such as copper. The
Group 1 metals are preferably sodium, potassium, lithium and
copper, more preferably sodium or potassium, and more preferably
sodium. The Group 2 metals of the metal base include the Group 2a
alkaline earth metals (e.g., magnesium, calcium, barium) as well as
the Group 2b metals such as zinc or cadmium. Preferably the Group 2
metals are magnesium, calcium, barium, or zinc, preferably
magnesium or calcium, more preferably calcium. Generally the metal
compounds are delivered as metal salts. The anionic portion of the
salt can be, e.g., hydroxide, oxide, carbonate, borate, or
nitrate.
An acidic gas is employed to accomplish the formation of the
overbased metal salt. The acidic gas is preferably carbon dioxide
or sulfur dioxide, and is most preferably carbon dioxide.
A promoter is a chemical employed to facilitate the incorporation
of metal into the basic metal compositions. The promoters are quite
diverse and are well known in the art, as evidenced by the cited
patents. A particularly comprehensive discussion of suitable
promoters is found in U.S. Pat. Nos. 2,777,874, 2,695,910, and
2,616,904. These include the alcoholic and phenolic promoters,
which are preferred. The alcoholic promoters include the alkanols
of one to twelve carbon atoms such as methanol, ethanol, amyl
alcohol, octanol, isopropanol, and mixtures of these. Phenolic
promoters include a variety of hydroxy-substituted benzenes and
naphthalenes a particularly useful class of phenols are the
alkylated phenols of the type listed in U.S. Pat. No. 2,777,874,
e.g., heptylphenols, octylphenols, and nonylphenols. Mixtures of
various promoters are sometimes used.
Patents specifically describing techniques for making basic salts
of the above-described sulfonic acids, carboxylic acids, and
mixtures of any two or more of these include U.S. Pat. Nos.
2,501,731; 2,616,905; 2,616,911; 2,616,925; 2,777,874; 3,256,186,
3,384,585; 3,365,396; 3,320,162; 3,318,809; 3,488,284; and
3,629,109.
The amount of the overbased material, that is, the detergent, is
preferably 0.05 to 5 percent by weight of the composition, more
preferably 0.05 to 3 percent, 0.1 to 1.5 percent, or most
preferably 0.2 to 1 percent by weight.
Preferably both a dispersant and a detergent are included in the
composition; preferably a succinimide dispersant and a calcium
overbased sulfonate detergent.
The compositions of the present invention can also contain a
polymeric viscosity index modifier, preferably in limited amounts,
that is, up to 10 percent by weight of the composition. Preferably
the amount of this component is 0 to 1 percent by weight, and in
one embodiment the traction fluids are substantially free from
polymeric viscosity index modifiers.
Polymeric viscosity index modifiers (VMs) are extremely well known
in the art and most are commercially available. Hydrocarbon VMs
include polybutenes, poly(ethylene/propylene) copolymers, and
hydrogenated polymers of styrene with butadiene or isoprene. Ester
VMs include esters of styrene/maleic anhydride polymers, esters of
styrene/maleic anhydride/acrylate terpolymers, and
polymethacrylates. The acrylates are available from RohMax and from
The Lubrizol Corporation; polybutenes from Ethyl Corporation and
Lubrizol; ethylene/propylene copolymers from Exxon and Texaco;
hydrogenated polystyrene/isoprene polymers from Shell;
styrene/maleic esters from Lubrizol, and hydrogenated
styrene/butadiene polymers from BASF.
Preferred VMs include acrylate- or methacrylate-containing
copolymers or copolymers of styrene and an ester of an unsaturated
carboxylic acid such as styrene/maleic ester (typically prepared by
esterification of a styrene/maleic anhydride copolymer). Preferably
the viscosity modifier is a polymethacrylate viscosity modifier.
Polymethacrylate viscosity modifiers are prepared from mixtures of
methacrylate monomers having different alkyl groups. The alkyl
groups may be either straight chain or branched chain groups
containing from 1 to 18 carbon atoms. When a small amount of a
nitrogen-containing monomer is copolymerized with alkyl
methacrylates, dispersancy properties are also incorporated into
the product. Thus, such a product has the multiple function of
viscosity modification, pour point depressancy and dispersancy.
Such products have been referred to in the art as dispersant-type
viscosity modifiers or simply dispersant-viscosity modifiers. Vinyl
pyridine, N-vinyl pyrrolidone and N,N'-dimethylaminoethyl
methacrylate are examples of nitrogen-containing monomers.
Polyacrylates obtained from the polymerization or copolymerization
of one or more alkyl acrylates also are useful as viscosity
modifiers. It is preferred that the viscosity modifier of the
present invention is a dispersant viscosity modifier.
In one embodiment a dispersant viscosity modifier is prepared by
polymerizing 57.5 parts methyl methacrylate, 12.7 parts butyl
methacrylate, 226.5 parts each of C.sub.9-11 methacrylate and
C.sub.12-15 methacrylate, 114.8 parts C.sub.16-18 methacrylate and
11.7 parts N-(3-(dimethylamino)propyl) methacrylamide in a staged
addition process. Details of the preparation of these and related
polymers are found in European Patent Application 750,031,
published Dec. 27, 1996.
The copolymers described above typically have a weight average
molecular weight (M.sub.w) of 10,000 to 500,000, more often 30,000
to 250,000, frequently 20,000 to 100,000 and polydispersity values
(M.sub.w /M.sub.n) of 1.2 to 5. Molecular weights of polymers are
determined using well-known methods described in the
literature.
Another optional component of the traction fluids of the present
invention is a phosphorus acid, a phosphorus acid salt, a
phosphorus ester, or mixtures thereof. The phosphorus acid or ester
can be of the formula (R.sup.1 X)(R.sup.2 X)P(X).sub.n X.sub.m
R.sup.3 or a salt thereof, where each X is independently an oxygen
atom or a sulfur atom, n is 0 or 1, m is 0 or 1, m+n is 1 or 2, and
R.sup.1, R.sup.2, and R.sup.3 are hydrogen or hydrocarbyl groups,
and preferably at least one of R.sup.1, R.sup.2, or R.sup.3 is
hydrogen. This component thus includes phosphorous and phosphoric
acids, thiophosphorous and thiophosphoric acids, as well as
phosphite esters, phosphate esters, thiophosphite esters, and
thiophosphate esters. It is noted that certain of these materials
can exist in tautomeric forms, and that all such tautomers are
intended to be encompassed by the above formula and included within
the present invention. For example, phosphorous acid and certain
phosphite esters can be written in at least two ways: ##STR5##
differing merely by the placement of the hydrogen. Each of these
structures is intended to be encompassed by the present
invention.
The phosphorus-containing acids can be at least one phosphate,
phosphonate, phosphinate or phosphine oxide. These pentavalent
phosphorus derivatives can be represented by the formula
##STR6##
wherein R.sup.1, R.sup.2 and R.sup.3 are as defined above. The
phosphorus-containing acid can be at least one phosphite,
phosphonite, phosphinite or phosphine. These trivalent phosphorus
derivatives can be represented by the formula ##STR7##
wherein R.sup.1, R.sup.2 and R.sup.3 are defined as above.
Generally, the total number of carbon atoms in R.sup.1, R.sup.2 and
R.sup.3 is at least 8, and in one embodiment at least 12, and in
one embodiment at least 16. Examples of useful R.sup.1, R.sup.2 and
R.sup.3 groups include hydrogen, t-butyl, isobutyl, amyl, isooctyl,
decyl, dodecyl, oleyl, C.sub.18 alkyl, eicosyl, 2-pentenyl,
dodecenyl, phenyl, naphtliyl, alkylphenyl, alkylnaphthyl,
phenylalkyl, naphthylalkyl, alkylphenylalkyl, and
alkylnaphthylalkyl groups.
In another embodiment, the phosphorus acid or ester is
characterized by at least one direct carbon-to-phosphorus linkage
such as those prepared by the treatment of an olefin polymer, such
as one or more of the above polyalkenes (e.g., polyisobutene having
a molecular weight of 1000) with a phosphorizing agent such as
phosphorus trichloride, phosphorus heptasulfide, phosphorus
pentasulfide, phosphorus trichloride and sulfur, white phosphorus
and a sulfur halide, or phosphorothioic chloride.
It is preferred that at least two of the X atoms in the above
structure are oxygen, so that the structure will be (R.sup.1
O)(R.sup.2 O)P(X).sub.n X.sub.m R.sup.3, and more preferably
(R.sup.1 O)(R.sup.2 O)P(X).sub.n X.sub.m H. This structure can
correspond, for example, to phosphoric acid when R.sup.1, R.sup.2,
and R.sup.3 are hydrogen. Phosphoric acid exists as the acid
itself, H.sub.3 PO.sub.4 and other forms equivalent thereto such as
pyrophosphoric acid and anhydrides of phosphoric acid, including
85% phosphoric acid (aqueous), which is the commonly available
commercial grade material. The formula can also correspond to a
mono- or dialkyl hydrogen phosphite such as dibutyl hydrogen
phosphite (a phosphite ester) when one or both of R.sup.1 and
R.sup.2 are alkyl, respectively and R.sup.3 is hydrogen, or a
trialkyl phosphite ester when each of R.sup.1, R.sup.2, and R.sup.3
is alkyl; in each case where n is zero, m is 1, and the remaining X
is O. The structure will correspond to phosphoric acid or a related
material when n and m are each 1; for example, it can be a
phosphate ester such as a mono-, di- or trialkyl monothiophosphate
when one of the X atoms is sulfur and one, two, or three of
R.sub.6, R.sub.7, and R.sub.8 are alkyl, respectively.
Phosphoric acid and phosphorus acid are well-known items of
commerce. Thiophosphoric acids and thiophosphorous acids are
likewise well known and are prepared by reaction of phosphorus
compounds with elemental sulfur or other sulfur sources. Processes
for preparing thiophosphorus acids are reported in detail in
Organic Phosphorus Compounds, Vol. 5, pages 110-111, G. M.
Kosolapoff et al., 1973.
Salts of the above phosphorus acids are well known. Salts include
ammonium and amine salts as well as metal salts. Zinc salts, such
as zinc dialkyldithiophosphates, are useful in certain
applications.
The amount of the above phosphorus acid, salt, or ester in the
traction fluid of the present invention is preferably an amount
sufficient to provide at least 0.01 percent by weight of phosphorus
to the fluids (calculated as P), preferably 0.01 to 0.1 percent,
and more preferably 0.03 to 0.06 or 0.05 percent by weight.
Another optional, but preferred, species in the traction fluids of
the present invention is one or more friction modifiers. Friction
modifiers include alkoxylated fatty amines, borated fatty epoxides,
fatty phosphites, fatty epoxides, fatty amines, borated alkoxylated
fatty amines, metal salts of fatty acids, fatty acid amides,
glycerol esters, borated glycerol esters, and fatty
imidazolines.
As one preferred example of a friction modifier, zinc salts of
fatty acids are well known materials. Fatty acids are generally
hydrocarbon-based carboxylic acids, both synthetic and naturally
occurring, preferably aliphatic acids, although acids containing
aromatic functionality are also included. Occasional heteroatom
substitution can be permitted in the hydrocarbyl portion of the
fatty acid, consistent with the definition of "hydrocarbyl," below.
Preferably the acid contains 14 to 30 carbon atoms, more preferably
16-24 carbon atoms, and preferably about 18 carbon atoms. The acid
can be straight chain (e.g. stearic) or branched (e.g.,
isostearic). The acid can be saturated or it can contain olefinic
unsaturation. A preferred acid is oleic acid, and the
correspondingly preferred salt is zinc oleate, a commercially
available material, the preparation of which is well known and is
within the abilities of the person skilled in the art.
The zinc salt can be a neutral salt, that is, in which one
equivalent of zinc is reacted with one equivalent of acid such as
oleic acid. Alternatively, the zinc salt can be a slightly basic
salt, in which one equivalent of a zinc base is reacted with
somewhat less than one equivalent of acid. An example of such a
material is a slightly basic zinc oleate, that is, Zn.sub.4
Oleate.sub.6 O.sub.1.
Alkyl-substituted imidazolines are also well known friction
modifying materials. They can generally be formed by the cyclic
condensation of a carboxylic acid with a 1,2 diaminoethane
compound. They generally have the structure ##STR8##
where R is an alkyl group and R.sup.1 is a hydrocarbyl group or a
substituted hydrocarbyl group, including --(CH.sub.2 CH.sub.2
NH).sub.n --H groups. Among the numerous suitable carboxylic acids
useful in preparing the imidazoline are oleic acid, stearic acid,
isostearic acid, tall oil acids, and other acids derived from
natural and synthetic sources. Specially preferred carboxylic acids
are those containing 12 to 24 carbon atoms including the 18 carbon
acids such as oleic acid, stearic acid, and isostearic acid. Among
suitable 1,2 diaminoethane compounds are compounds of the general
structure R--NH--C.sub.2 H.sub.4 --NH.sub.2, where R is a
hydrocarbyl group or a substituted hydrocarbyl group (e.g.,
hydroxyhydrocarbyl or aminohydrocarbyl). A preferred diamine is
N-hydroxyethyl-1,2-diaminoethane, HOC.sub.2 H.sub.4 NHC.sub.2
H.sub.4 NH.sub.2.
A preferred alkyl-substituted imidazoline is
1-hydroxyethyl-2-heptadecenyl imidazoline.
Another type of friction modifier includes borated epoxides, which
are described in detail in U.S. Pat. No. 4,584,115, and are
generally prepared by reacting an epoxide, preferably a hydrocarbyl
epoxide, with boric acid or boron trioxide. The epoxide can be
expressed by the general formula ##STR9##
wherein each R is independently hydrogen or a hydrocarbyl group
containing 8 to 30 carbon atoms, at least one of which is
hydrocarbyl. Also included are materials in which any two of the R
groups together with the atoms to which they are attached, for a
cyclic group, which can be alicyclic or heterocyclic. Preferably
one R is a hydrocarbyl group of 10 to 18 carbon atoms and the
remaining R groups are hydrogen. More preferably the hydrocarbyl
group is an alkyl group. The epoxides can be commercial mixtures of
C.sub.14-16 or C.sub.14-18 epoxides, which can be purchased from
ELF-ATOCHEM or Union Carbide and which can be prepared from the
corresponding olefins by known methods. Purified epoxy compounds
such as 1,2-epoxyhexadecane can be purchased from Aldrich
Chemicals. Alternatively this material can be a reactive equivalent
of an epoxide. By the term "reactive equivalent of an epoxide" is
meant a material which can react with a boronating agent (described
below) in the same or a similar manner as can an epoxide to give
the same or similar products. An example of a reactive equivalent
of an epoxide is a diol. Another example of a reactive equivalent
to epoxides is the halohydrins. Other equivalents will be apparent
to those skilled in the art. Other reactive equivalents include
materials having vicinal dihydroxy groups which are reacted with
certain blocking reagents. The borated compounds are prepared by
blending the boron compound and the epoxide and heating them at a
suitable temperature, typically 80.degree. to 250.degree. C., until
the desired reaction has occurred. Boronating agents include the
various forms of boric acid (including metaboric acid, HBO2,
orthoboric acid, H.sub.3 BO.sub.3, and tetraboric acid, H.sub.2
B.sub.4 O.sub.7), boric oxide, boron trioxide, and alkyl borates of
the formula (RO).sub.x B(OH).sub.y wherein X is 1 to 3 and y is 0
to 2, the sum of x and y being 3, and where R is an alkyl group
containing 1 to 6 carbon atoms. The molar ratio of the boronating
agent to the epoxide or reactive equivalent thereof is generally
4:1 to 1:4. Ratios of 1:1 to 1:3 are preferred, with 1:2 being an
especially preferred ratio. An inert liquid can be used in
performing the reaction. The liquid may be, for example, toluene,
xylene, or dimethylformamide. Water is formed and is typically
distilled off during the reaction. Alkaline reagents can be used to
catalyze the reaction. A preferred borated epoxide is the borated
epoxide of a predominantly 16 carbon olefin.
Other friction modifiers include diethoxylated long chain amines
such as N,N-bis-(2-hydroxyethyl)-tallowamine. Certain
phosphorus-containing materials, described above, can also serve as
friction modifiers, in particular, dialkylphosphites having alkyl
groups of 12 to 24 carbon atoms.
The amount of friction modifier or modifiers is preferably 0.01 to
2 percent by weight of the traction fluid composition. More
preferably it is 0.05 to 1.2 percent, and most preferably 0.1 to 1
percent by weight.
As used herein, the term "hydrocarbyl substituent" or "hydrocarbyl
group" is used in its ordinary sense, which is well-known to those
skilled in the art. Specifically, it refers to a group having a
carbon atom directly attached to the remainder of the molecule and
having predominantly hydrocarbon character. Examples of hydrocarbyl
groups include:
(1) hydrocarbon substituents, that is, aliphatic (e.g., alkyl or
alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents,
and aromatic-, aliphatic-, and alicyclic-substituted aromatic
substituents, as well as cyclic substituents wherein the ring is
completed through another portion of the molecule (e.g., two
substituents together form a ring);
(2) substituted hydrocarbon substituents, that is, substituents
containing non-hydrocar-bon groups which, in the context of this
invention, do not alter the predominantly hydrocarbon substituent
(e.g., halo (especially chloro and fluoro), hydroxy, alkoxy,
mercapto, alkylmercapto, nitro, nitroso, and sulfoxy);
(3) hetero substituents, that is, substituents which, while having
a predominantly hydrocarbon character, in the context of this
invention, contain other than carbon in a ring or chain otherwise
composed of carbon atoms. Heteroatoms include sulfur, oxygen,
nitrogen, and encompass substituents as pyridyl, furyl, thienyl and
imidazolyl. In general, no more than two, preferably no more than
one, non-hydrocarbon substituent will be present for every ten
carbon atoms in the hydrocarbyl group; typically, there will be no
non-hydrocarbon substituents in the hydrocarbyl group.
It is known that some of the materials described above may interact
in the final formulation, so that the components of the final
formulation may be different from those that are initially added.
For instance, metal ions (of, e.g., a detergent) can migrate to
other acidic sites of other molecules. The products formed thereby,
including the products formed upon employing the composition of the
present invention in its intended use, may not susceptible of easy
description. Nevertheless, all such modifications and reaction
products are included within the scope of the present invention;
the present invention encompasses the composition prepared by
admixing the components described above.
EXAMPLES
Samples are prepared in a base oil containing a fluidity modifier
and an additive package. In Examples 1-12 the identity and amounts
of components in the additive package is are follows:
Overbased Ca sulfonate detergents 1.07 percent by weight Overbased
Ca salicylate detergent 0.19 percent by weight Succinimide
dispersant 2.36 percent by weight Succinimide dispersants, 0.94
percent by weight borated and/or sulfurized Phosphoric acid (85%)
0.04 percent by weight Dialkyl hydrogen phosphite 0.19 percent by
weight Imidazoline and alkyl phosphite 0.12 percent by weight
friction modifiers Borated fatty epoxide 0.19 percent by weight
Fatty amine 0.02 percent by weight Dialkyl dimercaptothiadiazole
0.03 percent by weight Amine and/or sulfur containing 0.84 percent
by weight antioxidants Seal swell agent 0.57 percent by weight
Silicone and fluorosilicone 0.04 percent by weight antifoam agents
Diluent oil 0.63 percent by weight
Each of the preceding individual components contains the
conventional amount of diluent, if any, normally present in the
commercial material.
Compositions are prepared containing the above-identified additives
in the amounts shown (percent by weight), in a composition as shown
below. The low temperature viscosity of each composition is also
reported. Where multiple samples are prepared and tested, multiple
results are given:
Example: 1 2 3 4* 5 6 7* 8 9 10* 11 12 Hydrogenated linear dimer of
0 0 0 0 41.7 44.0 46.4 83.4 88.1 92.7 62.6 40.4 .alpha.-Me Styrene
Low m. w. hydrogenated 83.4 83.4 88.1 92.7 41.7 44.0 46.4 0 0 0
20.9 40.4 polybutene.sup.a 40 N naphthenic oil.sup.b 9.3 9.3.sup.c
4.6 0 9.3 4.6 0 9.3 4.6 0 9.3 9.0 Polybutene viscosity improver 0 0
0 0 0 0 0 0 0 0 0 3 Additive package (above) 7.3 7.3 7.3 7.3 7.3
7.3 7.3 7.3 7.3 7.3 7.3 7.3 Brookfield viscosity, Pa .multidot. s
(ASTM D2983) -30.degree. C. 13.4 11.2 17.4 22.5 13.2 16.8 22.0 17.8
24.0 34.0 15.2 21.5 13.0 16.8 21.5 13.6 18.4 34.0 -40.degree. C. 82
67 106 134 87 118 164 158 224 312 112 120 77 104 120 87 152 300
Kinematic viscosity (ASTM D445) (10.sup.6 m.sup.2 /sec [cSt])
40.degree. C. 27.2 26.0 30.4 34.0 22.1 24.2 26.6 19.5 21.3 23.3
20.6 30.2 27.2 30.4 30.2 22.1 19.5 23.3 100.degree. C. 5.1 4.61
4.98 5.30 4.14 4.34 4.55 3.75 3.92 4.13 4.0 4.7 4.67 4.99 4.7 4.2
3.77 4.12 Traction Coefficient Slide/roll 2.5% .059 .059 .059 .062
.071 .070 .074 .082 n. d. n. d. .076 .065 .061 .063 .065 .069 .079
5.0% .065 .065 .065 .068 .076 .075 .080 .086 n. d. n. d. .081 .071
.066 .068 .071 .074 .084 7.5% .068 .06 .069 .072 .078 .078 .082
.087 n. d. n. d. .083 .074 .070 .071 .074 .077 .086 10.0% .070 .07
.070 .074 .080 .080 .083 .088 n. d. n. d. .084 .075 .072 .073 .075
.079 .087 *Comparative .sup.a : Panalane .TM. L-14E .sup.b :
Diamond Shamrock 40 Pale .TM. except as noted .sup.c : Calumet
Hydrocal .TM. 38 n. d.: Not determined
The traction coefficient is determined generally as disclosed in
U.S. Pat. No. 3,975,278 and is a well-known measurement. More
particularly for the present testing, a MTM traction measurement
system from PCS Instruments is used. The test includes evaluating
the fluid behavior in an EHD contact formed between a polished 19.1
mm (3/4 inch) steel ball and a 46 mm diameter steel disk, each
independently driven to produce a sliding/rolling contact,
lubricated with the test specimen (each sample being about 30 g).
Testing is carried out at a Hertz contact pressure of 1.25 GPa. The
temperature of the test oil at the inlet of the contact is
continuously measured and controlled to 100.degree. C., and the
system given sufficient time to thermally stabilize. Rolling speed
is maintained at 2.5 m/s. A slide to roll ratio continuously
varying from 0% to 10% is achieved by changing the surface speeds
of both specimens simultaneously. Traction force is continuously
measured during each test, and traction coefficient is calculated
therefrom. Traction coefficient, .function..sub.t, is defined
by
where F.sub.t is the measured tangential or tractive force exerted
between the members and P.sub.n is the normal load or contact force
between the members.
Examples 13.
Overbased Ca sulfonate detergent 0.23% Succinimide dispersant 4.0%
Dialkyl hydrogen phosphite 0.11% phosphoric acid (85%, aqueous)
0.1% Sulfur-containing succinic ester/ 1.0% amide corrosion
inhibitor Amine and/or sulfur-containing 1.1% antioxidants
Alkyl-substituted thiadiazole 0.03% Borated fatty epoxide 0.2% Seal
swell agent 0.4% Alkenyl imidazoline 0.05% friction modifier
Alkoxylated fatty amine 0.01% Silicone and fluorosilicone 0.04%
antifoam agents Diluent oil 0.68%
Each of the preceding individual components contains the
conventional amount of diluent, if any, normally present in the
commercial material.
A traction fluid is prepared with and 41.4% hydrogenated linear
dimer of .alpha.-methyl styrene, 41.4% low molecular weight
hydrogenated polybutene (as above), 9.2% 40 N naphthenic oil, and
the above additive package.
The viscosity of the fluid thus prepared is measured, as in
Examples 1-12. The Brookfield viscosity at -30.degree. C. is 20.0
Pa.multidot.s and at -40.degree. C. is 138 Pa.multidot.s. The
kinematic viscosity is 28.5.times.10.sup.-6 m.sup.2 /s at
40.degree. C. and 5.0.times.10.sup.-6 m.sup.2 /s at 100.degree.
C.
Examples 14-18
The following compositions are prepared and tested (amounts given
in percent by weight, inclusive of conventional diluent oil):
Example: 14 15 16 17 18 Base oil: Hydrogenated linear dimer 79 0
84.95 83.4 40 of .alpha.-methyl styrene Low molecular weight hydro-
0 79 0 92 42.5 genated polybutene Fluidity modifier: 40 Neutral
naphthenic oil 20 1 0 0 5 Low m.w. poly-.alpha.-olefin 0 0 15 3 5
(Ethylflo .TM. 162) Detergent: Ca overbased sulfonate 1 10 0 0 5
Dispersant: Mannich dispersant 0 0 0.05 5 2.5
The examples immediately above may, optionally, contain other
additive components used in transmission fluids including
succinimide dispersants, phosphorus acids and esters, seal swell
agents, friction modifiers, antiwear agents, corrosion inhibitors,
antioxidants, and foam inhibitors.
Each of the documents referred to above is incorporated herein by
reference. Except in the Examples, or where otherwise explicitly
indicated, all numerical quantities in this description specifying
amounts of materials, reaction conditions, molecular weights,
number of carbon atoms, and the like, are to be understood as
modified by the word "about." Unless otherwise indicated, each
chemical or composition referred to herein should be interpreted as
being a commercial grade material which may contain the isomers,
by-products, derivatives, and other such materials which are
normally understood to be present in the commercial grade. However,
the amount of each chemical component is presented exclusive of any
solvent or diluent oil which may be customarily present in the
commercial material, unless otherwise indicated. It is to be
understood that the upper and lower amount, range, and ratio limits
set forth herein may be independently combined. As used herein, the
expression "consisting essentially of" permits the inclusion of
substances which do not materially affect the basic and novel
characteristics of the composition under consideration.
* * * * *